Such a heat exchanger is already known from Japanese Patent Application No. 8-275051 filed by the assignee of the present invention.
In general, the heat exchanger uses two or more types of fluids having different temperatures as mediums. For this reason, a difference in temperature is generated between members due to a difference in temperature between the fluids, and further, a difference in temperature is also generated between the stoppage and operation of the heat exchanger. Therefore, if the outer periphery of the heat exchanger is supported firmly in the casing, the following problems arise due to a difference in the amount of thermal expansion between the members.
When the heat exchanger is in a state having a temperature higher than that of the casing, there is a possibility that a thermal stress could be produced in the casing in the drawing direction to exert an adverse influence to the durability. On the other hand, when the heat exchanger is in a state having a temperature lower than that of the casing, there is a possibility that a thermal stress could be produced in the heat exchanger in the drawing direction to exert an adverse influence to the durability. Particularly, when the heat exchanger and the casing are formed from different materials, the above-described problems are further significant due to the thermal stress caused by a difference between the intrinsic thermal expansion coefficients of the materials.